1. Field of the Invention
The present invention is directed to the composition, methods of preparation and uses novel cucurbituril derivatives having various repeating units and cavities of various sizes.
2. Description of the Related Art
Cucurbituril is a macrocyclic compound whose preparation was first reported by Behrend et al. in 1905 (Liebigs Ann. Chem. 1905, 339, 1). According to their report, the condensation of glycoluril and excess formaldehyde in the presence of hydrochloric acid (HCl) produces an amorphous solid. Dissolution of the solid in hot concentrated sulfuric acid, dilution of the solution with water followed by slow cooling of the solution to room temperature produces a crystalline material. They wrongly characterized this substance as C10H11N7O4.2H2O solely based on elemental analysis. In 1981, this substance was rediscovered by Mock and coworkers (J. Am. Chem. Soc., 1981, 103, 7367). They correctly characterized it as a hexameric macrocyclic compound with composition of C36H36N24O12, which was also confirmed by X-ray crystal structure determination. They named it cucurbituril which we from now on refer to as cucurbit[6]uril.
Since then an improved preparation procedure for cucurbit[6]uril has been disclosed (DE 196 03 377 A1). According to this new procedure, in the presence of an acid, glycoluril and formaldehyde are reacted at 100xc2x0 C. or a higher temperature, and then the reaction mixture is further heated up to 150xc2x0 C. to concentrate the reaction mixture. Cooling the mixture to room temperature results in cucurbit[6]uril. This synthetic method can increase the yield of cucurbit[6]uril. However, it was reported to produce only the hexameric cucurbituril, cucurbit[6]uril, with improved yield. The cucurbituril derivatives having less or more than six monomers cannot be synthesized by the method. Moreover, the synthetic method requires a much higher reaction temperature, which makes it less practical.
In addition, decamethylcucurbit[5]uril, in which five dimethanodimethylglycoluril units form a cyclic structure by the condensation of dimethylglycoluril and formaldehyde, has been reported (Angew. Chem. Int. Ed. Engl. 1992, 31, 1475).
As described above, up to now, only two cucurbituril derivatives, cucurbit[n]uril with n=6 and decamethylcucurbit[n]uril with n=5, have been reported. The known cucurbituril derivatives are very limited in terms of types and cavity sizes (5.5 or less). Also, they are insoluble in common solvents such as water or methanol, and thus their applications are limited.
The first objective of the present invention is to provide novel cucurbituril derivatives with various-sized cavities and/or with enhanced solubilities in common solvents.
The second objective of the present invention is to provide easy preparation methods for the cucurbituril derivatives.
The third objective of the present invention is to provide the uses of the cucurbituril derivatives.
The first objective of the present invention is achieved by cucurbituril derivatives having the formula (1) 
where X is O, S or NH; R1 and R2 are independently selected from the group consisting of hydrogen, alkyl groups of 1 to 30 carbon atoms, alkenyl groups of 2 to 30 carbon atoms, alkynyl groups of 2 to 30 carbon atoms, alkylthio groups of 1 to 30 carbon atoms, alkylcarboxyl groups of 2 to 30 carbon atoms, hydroxyalkyl groups of 1 to 30 carbon atoms, alkylsilyl groups of 1 to 30 carbon atoms, alkoxy groups of 1 to 30 carbon atoms, haloalkyl groups of 1 to 30 carbon atoms, nitro group, alkylamine groups of 1 to 30 carbon atoms, amine group, aminoalkyl groups of 1 to 30 carbon atoms, unsubstituted cycloalkyl groups of 5 to 30 carbon atoms, cycloalkyl groups of 4 to 30 carbon atoms with hetero atoms, unsubstituted aryl groups of 6 to 30 carbon atoms, and aryl groups of 6 to 30 carbon atoms with hetero atoms; and n is an integer from 4 to 20, wherein the cucurbituril derivatives having the formula (1), where n=6, R1=H, R2=H and X=O, and n=5, R1=CH3, R2=H and X=O, are excluded.
The second objective of the present invention is achieved by new preparation methods for cucurbituril derivatives having the formula (1) 
where X is O, S or NH; R1 and R2 are independently selected from the group consisting of hydrogen, alkyl groups of 1 to 30 carbon atoms, alkenyl groups of 2 to 30 carbon atoms, alkynyl groups of 2 to 30 carbon atoms, alkylthio groups of 1 to 30 carbon atoms, alkylcarboxyl groups of 2 to 30 carbon atoms, hydroxyalkyl groups of 1 to 30 carbon atoms, alkylsilyl groups of 1 to 30 carbon atoms, alkoxy groups of 1 to 30 carbon atoms, haloalkyl groups of 1 to 30 carbon atoms, nitro group, alkylamine groups of 1 to 30 carbon atoms, amine group, aminoalkyl groups of 1 to 30 carbon atoms, unsubstituted cycloalkyl groups of 5 to 30 carbon atoms, cycloalkyl groups of 4 to 30 carbon atoms with hetero atoms, unsubstituted aryl groups of 6 to 30 carbon atoms, and aryl groups of 6 to 30 carbon atoms with hetero atoms; and n is an integer from 4 to 20.
The basic process of the invention used for the preparation of cucurbituril derivatives having formula (1) hereinabove comprises: (a1) adding 3 to 7 moles of an acid to 1 mole of compound (A) hereinbelow to form a mixture, adding 2 to 20 moles of alkylaldehyde (B) hereinbelow to the mixture, and stirring the mixture at 70 to 95xc2x0 C.; and (b1) stirring the reaction mixture at 95 to 105xc2x0 C. to complete the reaction. 
In another embodiment, the cucurbituril derivatives having formula (1) hereinabove may be formed by (a2) adding 0.1 to 1 moles of an acid to 1 mole of compound (A) hereinabove to form a mixture, adding 2 to 20 moles of alkylaldehyde (B) hereinabove to the mixture, and stirring the mixture at 70 to 85xc2x0 C., to obtain an intermediate in a gel state; and (b2) drying the gel, adding 3 to 7 moles of an acid for each mole of the dried intermediate, and stirring the reaction mixture at 70 to 105xc2x0 C.
In still another embodiment, the cucurbituril derivatives having the formula (1) hereinabove may be formed by (a3) placing compound (A) hereinabove, and 0.1 to 1 moles of an acid and 2 to 20 moles of alkylaldehyde(B) hereinabove for each mole of compound (A) hereinabove, in a high-pressure reactor, and reacting the mixture at 80 to 130xc2x0 C. to obtain an oligomeric intermediate in powder form; and (b3) adding 3 to 7 moles of an acid for each mole of the oligomeric intermediate, and stirring the mixture at 70 to 105xc2x0 C.
The reaction products of steps (b1), (b2) and (b3) are a mixture of two or more cucurbituril derivatives having the formula (2) with n of a value from 5 to 20, depending on the reaction conditions.
The typical reaction products of steps (b1), (b2) and (b3) are a mixture of 5-30% of the cucurbituril derivative having n=5, 30-70% of the cucurbituril derivative having n=6, 5-30% of the cucurbituril derivative having n=7, 2-15% of the cucurbituril derivative having n=8, and 1-10% of the cucurbituril derivative having n=9 through 20.
Each of the above three methods for preparing cucurbituril derivatives having the formula (1) hereinabove, may further comprise: (c1) crystallizing the cucurbituril derivative having the formula (1) with n=8 from the product mixtures obtained in step (b1), (b2) or (b3); (d1) diluting the remaining solution after step (c1) with water and acetone to produce a precipitate which is filtered and further treated in step (e1), and removing the solvent from the resulting filtrate to obtain the cucurbituril derivatives having the formula (1), with n ranging from 9 to 20; and (e1) partially dissolving the precipitate obtained in step (d1) in water to obtain the cucurbituril derivatives with n=5 and 7 from the water soluble fraction, and the cucurbituril derivative with n=6 from the water insoluble fraction. Separation of the cucurbituril derivative with n=5 from the cucurbituril derivative with n=7 in the water soluble fraction, which is obtained from step (e1), is achieved by partial precipitation using a mixed solvent of water and methanol.
In another aspect of the present invention, the cucurbituril derivatives having the formula (1) prepared by the inventive methods can be utilized to remove organic dyes from waste water, heavy metal from water, and radioactive isotopes from radioactive wastes, to capture and remove unpleasant odor, and air pollutants such as carbon monoxide, carbon dioxide, NOx and SOx, and to deodorize and decolorize livestock waste water and ironwork waste water. Also, the cucurbituril derivatives having the formula (1) are applicable in manufacturing sensors for sensing ammonium ions, organic amines, amino acid derivatives, nucleic acid bases, alkali metal or alkaline earth metal ions. The cucurbituril derivatives having the formula (1) can be used as additives to polymers, cosmetics, artificially scented papers or textiles, pesticides and herbicides, and drugs, and used as drug carriers. The cucurbituril derivatives having the formula (1) can be used for extraction and purification of fullerene or caborane compounds, and used as packing materials of chromatographic columns, as additives to gas separation membranes, as catalysts for various chemical reactions.
For such applications, any cucurbituril derivative synthesized in the present invention can be used. A mixture of the cucurbituril derivatives from step (b1), (b2) or (b3) can be used for the above-listed purposes without further purification.